The present invention relates to an integrated circuit comprising a circuit board in which a conductive layer having a desired pattern is formed on a metal substrate through an insulating layer, and a circuit element nondetachably mounted on the insulating layer and having a nonvolatile storage content which can be rewritten by an external operation.
Conventionally, a technique disclosed in Japanese Patent Publication No. 63-131146 is known as an integrated circuit having a pair of metal substrates, wherein conductive layers are adhered to each metal substrate through an insulating layer, a circuit element is fixed to each conductive layer, and the conductive layers are connected through a connecting substrate, and are separated from each other to face each other. In addition, a method of manufacturing the integrated circuit is disclosed in Japanese Patent Publication No. 46-13234 and comprises the step of anode-oxidizing at least one major surface of an aluminum substrate to form a thin aluminum oxide layer on the substrate surface, the step of selectively bonding and forming a resistive material and a high-conductivity material on the thin aluminum oxide film to form a plurality of circuit elements, the step of fixing transistor pellets on lead portions formed by selectively bonding the high-conductivity material, and the step of sealing at least all the circuit elements.
In the integrated circuit formed in this manner of Japanese Patent Application No. 46-13234, on a circuit board in which a conductive layer of a desired pattern is formed on a metal substrate through an insulating layer, at least one memory element is nondetachably mounted as a so-called bare chip on the insulating layer.
The integrated circuit formed in this manner may be employed in a vehicle in view of its compact structure and low cost. However, when the integrated circuit having a metal substrate is actually used in a vehicle, various tests must be conducted in a development process, so that data stored in the memory element must be rewritten as needed, and a control program must be updated.
However, the memory element is directly mounted on a circuit as a bare chip. When the memory element is once mounted, it cannot be detached. Thus, it is difficult to perform processing of a storage content, for example, it is difficult to rewrite data, update a control program, monitor a storage content, and the like. As a result, a degree of freedom in development is considerably restricted.